/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_min_q31.c
 * Description:  Minimum value of a Q31 vector
 *
 * $Date:        18. March 2019
 * $Revision:    V1.6.0
 *
 * Target Processor: Cortex-M cores
 * -------------------------------------------------------------------- */
/*
 * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed under the Apache License, Version 2.0 (the License); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "arm_math.h"

/**
  @ingroup groupStats
 */


/**
  @addtogroup Min
  @{
 */

/**
  @brief         Minimum value of a Q31 vector.
  @param[in]     pSrc       points to the input vector
  @param[in]     blockSize  number of samples in input vector
  @param[out]    pResult    minimum value returned here
  @param[out]    pIndex     index of minimum value returned here
  @return        none
 */
#if defined(ARM_MATH_MVEI)

#include "arm_helium_utils.h"

void arm_min_q31(
	const q31_t *pSrc,
	uint32_t blockSize,
	q31_t *pResult,
	uint32_t *pIndex)
{
	uint32_t  blkCnt;           /* loop counters */
	q31x4_t vecSrc;
	q31x4_t curExtremValVec = vdupq_n_s32(Q31_MAX);
	q31_t minValue = Q31_MAX, temp;
	uint32_t  idx = blockSize;
	uint32x4_t indexVec;
	uint32x4_t curExtremIdxVec;
	mve_pred16_t p0;


	indexVec = vidupq_u32((uint32_t)0, 1);
	curExtremIdxVec = vdupq_n_u32(0);

	/* Compute 4 outputs at a time */
	blkCnt = blockSize >> 2U;
	while (blkCnt > 0U) {
		vecSrc = vldrwq_s32(pSrc);
		pSrc += 4;
		/*
		 * Get current min per lane and current index per lane
		 * when a min is selected
		 */
		p0 = vcmpleq(vecSrc, curExtremValVec);
		curExtremValVec = vpselq(vecSrc, curExtremValVec, p0);
		curExtremIdxVec = vpselq(indexVec, curExtremIdxVec, p0);

		indexVec = indexVec +  4;
		/*
		 * Decrement the blockSize loop counter
		 */
		blkCnt--;
	}

	/*
	 * Get min value across the vector
	 */
	minValue = vminvq(minValue, curExtremValVec);
	/*
	 * set index for lower values to min possible index
	 */
	p0 = vcmpleq(curExtremValVec, minValue);
	indexVec = vpselq(curExtremIdxVec, vdupq_n_u32(blockSize), p0);
	/*
	 * Get min index which is thus for a min value
	 */
	idx = vminvq(idx, indexVec);


	/* Tail */
	blkCnt = blockSize & 0x3;
	while (blkCnt > 0U) {
		/* Initialize temp to the next consecutive values one by one */
		temp = *pSrc++;

		/* compare for the minimum value */
		if (minValue > temp) {
			/* Update the minimum value and it's index */
			minValue = temp;
			idx = blockSize - blkCnt;
		}

		/* Decrement loop counter */
		blkCnt--;
	}
	/*
	 * Save result
	 */
	*pIndex = idx;
	*pResult = minValue;
}
#else
void arm_min_q31(
	const q31_t *pSrc,
	uint32_t blockSize,
	q31_t *pResult,
	uint32_t *pIndex)
{
	q31_t minVal, out;                             /* Temporary variables to store the output value. */
	uint32_t blkCnt, outIndex;                     /* Loop counter */

#if defined (ARM_MATH_LOOPUNROLL)
	uint32_t index;                                /* index of maximum value */
#endif

	/* Initialise index value to zero. */
	outIndex = 0U;
	/* Load first input value that act as reference value for comparision */
	out = *pSrc++;

#if defined (ARM_MATH_LOOPUNROLL)
	/* Initialise index of maximum value. */
	index = 0U;

	/* Loop unrolling: Compute 4 outputs at a time */
	blkCnt = (blockSize - 1U) >> 2U;

	while (blkCnt > 0U) {
		/* Initialize minVal to next consecutive values one by one */
		minVal = *pSrc++;

		/* compare for the minimum value */
		if (out > minVal) {
			/* Update the minimum value and it's index */
			out = minVal;
			outIndex = index + 1U;
		}

		minVal = *pSrc++;
		if (out > minVal) {
			out = minVal;
			outIndex = index + 2U;
		}

		minVal = *pSrc++;
		if (out > minVal) {
			out = minVal;
			outIndex = index + 3U;
		}

		minVal = *pSrc++;
		if (out > minVal) {
			out = minVal;
			outIndex = index + 4U;
		}

		index += 4U;

		/* Decrement loop counter */
		blkCnt--;
	}

	/* Loop unrolling: Compute remaining outputs */
	blkCnt = (blockSize - 1U) % 4U;

#else

	/* Initialize blkCnt with number of samples */
	blkCnt = (blockSize - 1U);

#endif /* #if defined (ARM_MATH_LOOPUNROLL) */

	while (blkCnt > 0U) {
		/* Initialize minVal to the next consecutive values one by one */
		minVal = *pSrc++;

		/* compare for the minimum value */
		if (out > minVal) {
			/* Update the minimum value and it's index */
			out = minVal;
			outIndex = blockSize - blkCnt;
		}

		/* Decrement loop counter */
		blkCnt--;
	}

	/* Store the minimum value and it's index into destination pointers */
	*pResult = out;
	*pIndex = outIndex;
}
#endif /* defined(ARM_MATH_MVEI) */

/**
  @} end of Min group
 */
